With the advent of the Internet and the ever increasing miniaturization and integration of electronic circuits, new possibilities have begun to emerge in the field of data communication networks.
Several applications, such as industrial automation and monitoring, localization of personal and assets, and defense and security management, have specific requirements that cannot be met with wired networks or existing wireless networks.
In order to provide a solution for these types of applications, significant new research has been conducted in the past ten years to develop new and more efficient wireless network systems and protocols.
This research has resulted in the appearance of a plethora of proprietary and non-proprietary wireless networking technologies. Some, such as WLAN (IEEE 802.11), WiMAX (IEEE 802.16), Bluetooth (IEEE 802.15.1), ZigBee (IEEE 802.15) and the upcoming SP100 protocol are standard non-proprietary wireless networking protocols. Standard networking technologies generally involve trade-offs between numerous competing issues (scalability, topology, energy consumption, range, frequency, etc.). They are therefore difficult to adequately tailor to the specific needs of particular applications. This invention, in contrast, does not operate on a standard and can be tailored with a high degree of specificity to particular applications. This invention is also different from other proprietary network protocols, such as the TSMP from Dust Networks and the SensiNet® from Sensicast, two other non-standard wireless networking protocols.
Beacon-based networks have been implemented in some cases. While these networks have facilitated some useful advances, they either only operate in star configurations or consume too much energy to be battery-powered. Many applications mandate a mesh network that is highly scalable, in terms of the maximum number of hops and node density for which the network remains reliable. Many applications also require a network connection time in the order of seconds. Mesh network techniques that rely on central synchronization cannot meet these demands.
Ad hoc communication in mesh networks usually implies local allocation of communication resources without a central host. Low energy consumption must prevail in allocating these resources.
Real-time tracking of mobile terminals in underground or confined environments (e.g. underground mines, navy vessels) is challenging because: (1) Mobile terminals cannot receive satellite or cellular signals from Wide Area Networks (WAN) [e.g. GPS does not work]; (2) Deploying Local Area Network (LAN) infrastructure is prohibitively expensive, operationally impractical and/or unreliable because (a) RF signal propagation is non-line-of-sight and confined to tunnels, corridors or rooms with waveguide constraints; (b) Power outlets are scarce and installing additional power wiring, connectors and adapters is a tedious undertaking; (c) Many sites are in remote areas and/or in developing countries where skilled labor for installation and maintenance of telecom networks are in short supply; (d) Wiring is prone to damage.
From the foregoing, it appears that there is a need for a novel wireless network technology which obviates the above-mentioned drawbacks.